Spectroscopy with electronic terahertz techniques

Daniel W. van der Weide; Janusz A. Murakowski; Fritz Keilmann

doi:10.1117/12.361046

9 September 1999 Spectroscopy with electronic terahertz techniques

Daniel W. van der Weide, Janusz A. Murakowski, Fritz Keilmann

Proceedings Volume 3828, Terahertz Spectroscopy and Applications II; (1999) https://doi.org/10.1117/12.361046
Event: Industrial Lasers and Inspection (EUROPTO Series), 1999, Munich, Germany

Abstract

We report gas absorption spectra and energetic material reflection spectra measured with an all-electronic terahertz (THz) spectrometer. This instrument uses phase-locked microwave sources to drive picosecond GaAs nonlinear transmission lines, enabling measurement of both broadband spectra and single lines with hertz-level precision, a new mode of operation not readily available with optoelectronic THz techniques. We take two approaches to coherent measurements: (1) spatially combining the freely propagating beams from two coherent picosecond pulse generators, or (2) using a more conventional coherent source/detector arrangement with sampling detectors. The first method employs a dual-source interferometer modulating each harmonic of one source with a precisely-offset harmonic from the other source - both sources being driven with stable phase-locked synthesizers - the resultant beat frequency can be low enough for detection by a standard composite bolometer. Room-temperature detection possibilities for the DSI include antenna-coupled Schottky diodes. Finally, we have recently introduced a reflectometer based on serrodyne modulation of a linearized delay line, using a technique that is process-compatible with pulse generator circuits.

Citation Download Citation

Daniel W. van der Weide, Janusz A. Murakowski, and Fritz Keilmann "Spectroscopy with electronic terahertz techniques", Proc. SPIE 3828, Terahertz Spectroscopy and Applications II, (9 September 1999); https://doi.org/10.1117/12.361046

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